The active matrix panel display elements possess many merits of thin frame, power saving, no radiation, etc. and have been widely used. The Organic Light Emitting Diode (OLED) display technology is a flat panel display technology which has great prospects for development. It possesses extremely excellent display performance, and particularly the properties of self-illumination, simple structure, ultra thin, fast response speed, wide view angle, low power consumption and capability of realizing flexible display, and therefore is considered as the “dream display”. Meanwhile, the investment for the production equipments is far smaller than the Thin Film Transistor-Liquid Crystal Display (TFT-LCD). It has been favored by respective big display makers and has become the main selection of the third generation display element of the display technology field. At present, the OLED has reached the point before mass production. With the further research and development, the new technologies constantly appear, and someday, there will be a breakthrough for the development of the OLED display elements.
The prior art mainly uses a structure in which a white organic light emitting diode (WOLED) and a color filter (CF) are stacked to realize full color of the OLED display device. The current WOLED mainly uses a two-layer laminated structure of blue plus yellow light emitting layer or three-layer laminated structure of blue plus red plus green light emitting layer to realize white light. The white light spectrum is wider. When the white light is separated into three primary colors by using a color filter, since the spectrum of red light and green light is wider, the color purity of red light and green light is lower, and the color gamut of the WOLED display is not wide enough. Meanwhile, when the white light is separated into red light and green light by using the color filter, only the red light and the green light in the white light spectrum can be utilized, and the energy loss of the blue light in the white light spectrum is large, and the energy utilization rate is low, resulting in the higher energy consumption of the WOLED display.
Quantum Dot (QD) refers to a semiconductor crystal grain having a particle diameter of 1-100 nm. Since the particle size of QD is small, the quantum Boolean effect is smaller or closer to the exciton Bohr radius of the corresponding material, and the continuous energy band structure of the material is transformed into a discrete energy level structure. Under the excitation of the external light source, the electrons will have transition and emit fluorescence. QD's special discrete energy level structure makes the half-wave width thereof narrower, so QD can emit high-purity monochromatic light, which has higher luminous efficiency than traditional displays. Meanwhile, since the band gap of the QD is greatly affected by the size of the QD, and the light of different wavelengths can be excited by adjusting the size of the QD or using QDs of different compositions.